Typically, cam shaft and crank shaft bearings in internal combustion engines become worn and damaged due to a multitude of reasons and must therefore be repaired and/or replaced. Lack of lubrication and/or overheating of such engines are attributable to many such problems. Rectification of this situation usually requires re-boring of the engine head or block along the axis of the cam shaft or crank shaft so that new oversized bushings and bearings or an oversized cam shaft or crank shaft can be installed in place of the worn parts. Because cam shaft and crank shaft bearing bores are positioned and located in alignment in either the cylinder head or the engine block, re-boring of such surfaces is difficult since there is a need to carefully center and align the boring tool within such bores so that all surfaces can be accurately re-bored simultaneously. Techniques currently available for accomplishing this task typically include a pair of external support arm members attachable to the boring machine itself, the support arm members including means for holding the boring bar and each being movable exterior of the cylinder head or block to properly support the boring bar for the particular boring application. Due to the construction of many overhead cam cylinder heads and, more particularly, the Ford Escort overhead cam cylinder head, the known conventional techniques for externally supporting the boring bar within the in-line cam shaft bores of such cylinder heads do not provide adequate support for re-boring those cam bores located towards the center of the cylinder head. This is true because the construction of such overhead cam cylinder heads such as the Ford Escort head are such that they will not allow engagement of the conventional overhead support arms associated with the known boring machines with the boring bar at a central location therealong. This lack of sufficient central support causes the boring bar to chatter and vibrate when re-boring these particular bores and this produces an unacceptable, out-of-round bore.
Since, today, more and more vehicles are equipped with overhead cam cylinder heads, there is a growing necessity for in-line boring of such cylinder heads in order to repair operating damage thereto as outlined above. For example, in-line boring may be required to restore proper cam shaft alignment, or such machining operation may be necessary to repair bearing surfaces damaged by spun journals. Also, importantly, since todays modern engines run at much higher operating temperatures, damage due to overheating such as blown head gaskets and/or warped cylinder heads are likewise commonplace. A need therefore exists for support means capable of adequately supporting a boring bar at a central location therealong when in-line boring certain types of overhead cam cylinder heads and other like mechanisms such as the Ford Escort style cylinder head.